High velocity tool unit for dental engines



May 9, 1961 F. G. MoULDs HIGH VELOCITY Toor. UNIT FOR DENTAL ENGINES ATTORNEYS May 9, 1961 F. G. MouLDs 2,983,047

HIGH VELOCITY TooL UNIT FOR DENTAL ENGINES Filed July l1, 1957 2 SheetsSheet 2 E4 -I E l Fles.

INVENTOR. FRANCIS GEORGE MQULDS MIA/ME ATTORNEYS United States Passt 1Q HIGH VELCITY TOOL UNIT FOR DENTAL ENGINES 1 Claim. (Cl. 32-27) The invention relates to improvements in dental handpieces or drilling instruments.

The object of this invention is to provide a means and instrument which is readily attachable to the ordinary dental engine by means of the conventional wrist pulley and by which rotational cutting instruments such as dental burs and diamonds may be rotated at high rates of speed and in which the axis of rotation of such cutting instruments will be positionedV at an angle of from 90 degrees to 120 degrees to the longitudinal axis of the handpiece and in which rotational cutting instruments will be positively driven by a rotating tool socket and will be securely iixed in such tool socket but at the same time may be readily removed for replacement or interchange.

A further object of this invention is to provide a simple means and mechanism whereby liquids such as water, saliva and blood will be positively excluded from the interior of the handpiece without the use of seals comprising moving frictional parts and without the introduction of air or gas under pressure to the instrument.

A further object of this invention is to provide a means whereby 4such high speed handpiece may be readily interchanged with conventional handpieces designed to operate at lower speeds.

A further object of this invention is to provide a rotational tool socket for a high speed dental handpiece which will so retain and position the inserted rotational cutting instrument that the axis of rotation of the cutting instrument will substantially coincide with its longitudinal axis and with the axis of rotation of the tool socket, whereby the tool socket and cutting instrument may rotate as a unit without excessive vibration and without eccentric motion, even when operating at speeds below the maximum and whereby transmitted vibration to the tooth undergoing operative procedure may be maintained at a minimum. i

To vthis end lthe invention consists in a self-contained high ratio belt operated step-up transmission unit by means of which the rotational force supplied by the dental engine is transmitted to a rotational tool socket positioned at 90 degrees to 120 degrees to the longitudinal axis of the hand piece. The invention further consists in the construction of the rotary tool socket by which the tool is held from displacement with its axis of rotation coincident with the axis of the socket and is therefore driven without slippage, vibration or eccentric motion.

The invention further consists in the means for preventing suction into the housing enclosing the rotating mechanism for the tool, of blood, water, saliva or tooth debris. Still further the invention consists in the more specific construction as hereinafter set forth.

yIn the accompanying drawings:

Fig. 1 is a central longitudinal section through the replacement unit.

Fig. 2 is a plan View thereof.

Fig. 3 is an end elevation.

Figs. 4, 5 and 6 are cross sections respectively on lines 4 4, V5-5 and 6-6 of Fig. 1.

. immettere 1.96.1.

. 2 t l t.

Fig. 7 is a bottom plan view of Fig. 2 with the belt enclosing housing removed. Y' j Fig. v8 is an axial section through the rotary tool socket and its mounting in the hand piece. j

Fig. 9 is an elevation of the upper end of the tool socketi showing the means for attaching the tool thereto.

Fig. 10 is a plan view of Fig. 8 with cap screw D8 removed. Y

fFig. 11 is a plan view of a disc having crossed grooves.

Fig. 12 is a cross section thereof.

Fig. 13 is a plan'view of a modied disc.

Fig. 14 is a cross section thereof. j Fig. l5 is a plan view of another modified disc.

Fig. 16 is a cross section thereof. l n

In most dental engines a belt transmission conveys power from the motor through jointed arms to the hand piece which carries the rotary tool socket. This same belt transmission may-be retained for drivingmy high velocity unit but it is supplemented by a high ratio stepup transmission housed within lthe hand piece. The unit includes a pulley Ysubstituted for the conventional drive pulley on the hand piece so that Vin making the ex-f` change the belt is removed from the pulley of the replaced member and engaged with a pulley of the unit which is in the same position. Also the hand piece has a detachable swivel connection to the adjacent member of the dental engine, theaxis of which is in the plane of said belt transmission.

As shown in Fig. 1 the unit comprises a hand piece having a rotary tool socket -at its free end, the so-called drive pulley at its opposite end and a high ratio step-up belt transmission therebetween. The swivel connection between the hand piece and the adjacent member of `the dental engine preferably comprises a ver-tical pin (not shown) on the engine and a socket member- A connected to the hand piece for detachably engaging said pin. The member A has a laterally offset upward extension A' with a socket A2 at its upper end for receiving the end of a pin A2, the axis of which is perpendicular to the axis'of the socket A and extends in the same plane. A set screw A4 secures the pin A3 and the socket A2. B is the drive pulley journaled on the pin A3 to locate its driving belt (not shown) in the plane of the 'axis of the socket A. Adjacent to the pulley B and integral with it, as illustrated in Fig. l, or attached to it by a suitable driving mechanism, such as a frictional clutch, is a pulleyV Bof larger diameter, which, in normal operation turns at the same angular speed as pulley B, ball bearings B2 being between said pulleys and said pin. The hand piece comprises rod members C and 'C' longitudinally adjustably secur'edvfto each other andfalso a'hollow member D'securedto'the member I2, hereinafter described in detail, and extending beyond the member C at an angle to the longitudinal axis of the latter and carrying the rotary tool socket E at its outer end. The axis of this tool socket is preferably degrees to 120 degrees to the longitudinal axis of the member D. The member C is formed with a longitudinal socket C2 for swivelling it upon an extension of the pin A3 beyond the pulleys B and B thereon. A screw C4 having its inner end portion engaging a groove A5 retains the member C on the pin A3 while permitting the free swivelling movement.

The tool socket E is formed of a tubular member engaging a cylindrical end portion D of the member D. The longitudinal central portion of the socket forms a pulley E' having spaced anges E2 and ball bearings E3 and E.l adjacent these flanges journal the socket within the portion D. L is a spacer separating the outer races of the ball bearings E3 and E7 to prevent excessive preloading. The socket is internally cylindrical through the greater portion of its length to receive the shank F of a tool member but at the inner end the socket is at- 3 tened at E4 to receive the attened tab F' of said shank to impart positive Irotation thereto. For retaining the shank in the socket a U-shaped spring clip E5 embraces the 'socket engaging cross channels E3 therein and also engaging notches F2 in the opposite edges of the tab F. Thus the tool shank when fully inserted in the socket will be retained therein against accidental displacement but may be Withdrawn at any time for exchange of tools. The portion D has an integral wall D2 at one end thereof apertured for the passage outward therethrough of the entrance end portion of the socket. At the opposite end is a removable screw cap D3 permitting the assembly of the parts.

The high ratio step-up transmission comprises a single seamless belt between the pulleys B' and E. The ratio of the diameters of these pulleys may be as high as for instance six to one inasmuch as the pulley E is small in diameter, being only greater than the shank of the tool by the wall thickness of the socket. To direct the belt between these pulleys there are pairs of idler pulleys G, G', G2, G3. The pulleys G, G are supported on a bracket H which is sleeved on the end portion of the rod C to extend laterally therefrom beyond the pulley B'. These pulleys G and G are secured at opposite sides of the bracket H by screws H and H2 and ball bearings H3. Their axes are at an angle to each other and to the bracket so as to receive portions of the belt in the plane of the pulley B redirecting them to extend longitudinally of the hand piece in fairly close proximity to each other. Thus the length of the wrap of the belt around the pulley B is increased by the close proximity to each other of the pulleys G, G. The idler pulleys G2, G3 are located at approximately the change of angle between the longitudinal axes of the members C, C and that of the member D. The member C' is bifurcated in its outer end portions C5 to receive between the furcations thereof these pulleys which have a common axis. Also the member `C is channeled at C6 to receive the portions of the belt between the pulleys G, G' and G2, G3. To house the belt a tapering tube I surrounds the members C and C' and is secured to the latter by a screw I'. There is also a tubular housing I2 of uniform diameter between the member I and the member D. To retain the different portions of the belt in their -respective planes some of the pulleys, including B', E', G and G', are slightly crowned, while the pulleys G2, G3 have slightly flaring opposite end portions. The belt is also of dat oblong cross section. To tighten the belt the members C and C may be adjusted relative to each other. As specically shown the member C has a portion C'I of rectangular cross section which engages a groove C8 of similar cross section in the member C. A clamping screw C9 holds these members in adjusted position.

In operation the high velocity rotation of the tool .4 socket and the pulleys surrounding the same acts as a centrifugal air pump lowering the pressure Within the housing portion D. As there is a slight clearance between the socket and the aperture in the end Wall D2 there will be suction therethrough tending to draw within the member D blood, water, saliva or tooth debris. Such result Imay be avoided by developing outside said member adjacent to said aperture a drop in pressure which is substantially equally low to that inside. For this purpose I preferably mount a disc I outside but close to the casing D which rotates with the socket and by centrifugal action lowers the pressure. The disc I may be conveniently mounted on the shank of the tool. The face portion of the disc J, adjacent to the face D2 of the housing D may be essentially smooth. Preferably, however, said face portion of the disc I may be constructed with either grooves or vanes to improve the efciency of operation, as illustrated in Figs. 11 to 16, inelusive.

Considerable heat will be developed by the rotation of the cutting tool in the performance of its work. I therefore preferably arrange a small diameter conduit K extending outside the member D into proximity to the disc J with a discharge aperture K' therein directed towards the cutting end of the tool. A spray of water and air will be constantly discharged through this aperture K' directed against the cutting end of the tool to absorb the generated heat.

What I claim as my invention is:

In dental apparatus, a hand piece, a rotary tool socket housed therewithin with the tool projecting out through an aperture in the housing, the rotation of said socket developing a less than atmospheric pressure within the housing adjacent to said aperture, and means for creating outside the housing adjacent said aperture au equally low air pressure to prevent suction inward through said apertures, said means including a disc outside of but adjacent to said housing and connected to rotate with said socket, where the side of said disc facing said housing has vanes formed therein for aiding in the development of the reduced pressure.

References Cited in the tile of this patent UNITED STATES PATENTS 1,769,160 Ollesheimer July l. 1930 2,701,388 Downey Feb. 8, 1955 2,791,835 Staunt May 14, 1957 2,824,370 Page Feb. 25, 1958 FOREIGN PATENTS 239,460 Switzerland Ian. 16, 1946 732,213 Great Britain June 22, 1955 181,358 Austria Mar. 10, 1955 

